NATIONAL OPEN UNIVERSITY OF NIGERIA
UNIVERSITY VILLAGE, PLOT 91 CADASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI – ABUJA.
FACULTY OF SCIENCES
DEPARTMENT OF PURE AND APPLIED SCIENCES
JULY 2018 EXAMINATION
COURSE CODE: CHM 303
COURSE TITLE: INORGANIC CHEMISTRY III
COURSE UNIT: 3
TIME: 2 ⅟2 HOURS
INSTRUCTION: Question one is compulsory. Answer question one and any other four questions.
QUESTION ONE
1ai) Mention the principal source of Ne, Ar and Xe and how these elements can be obtained from their source. 3 mks
1aii) Write an equation representing the reaction between xenon and fluorine at 700k, 6 atm.
31/2 mks
1bi) Explain why Group IIIB elements, unlike group I and II are essentially covalent or contain an appreciable amount of covalent character. 2 mks
1bii) Write short note on formation of complexes by transition metals. 7 mks
1ci) Depending on chemical composition, classify minerals of metals. 21/2 mks
1cii) Why is Carbon a preferred reducing agent in commercial metallurgy? 2mks
1ciii) Carbon reduction is not used to obtain certain metals from their ores, explain 2 mks
QUESTION TWO
2ai) What kind of oxides is formed when oxygen reacts with;
-Group I and II metals
-Sulphur and Phosphorus 2 mks
2aii) How do the elements of Group IVA excluding carbon make more than four covalent bonds. 2 mks
2bi) Why are the compounds of Sc3+, Ti4+ and Zn2+ white or colourless. 4mks
2bii) Differentiate between gangue and slag. 4 mks
QUESTION THREE
3ai) Explain the chemistry behind the steady increase in boiling points from He to Rn? 31/2 mks
3aii) State one characteristic and application of noble gases. 2mks
3bi) Complete the chemical equation for the reaction;
XeF2 + H2 2 mks
3bii) Briefly explain the meaning and implication of lanthanide contraction. 41/2mks
QUESTION FOUR
4ai) Fill in the shapes of the following compounds.
Column I
Column II
XeF4
XeOF4
XeF4
XeF6
2 ½ mks
4aii) Using Valence Shell Electron Pair Repulsion Theory (VSEPR), justify the shape of XeF2 compounds. 4 mks
4b) Comment on colour of transition metal compounds. 5½mks
QUESTION FIVE
a) Give reasons for the following:
Four reasons why beryllium is different from other members of group IIA. 4 mks
Why caesium is a more reducing agent than sodium. 2 mks
b) Use the Valence Bond Theory to explain the formation of coordination compounds. 6 mks
QUESTION SIX
a) Explain the chemistry behind beneficiation of ores. 4 mks
b) Distinguish between the following methods of beneficiation of ores.
Gravity 4 mks
Magnetic separation 4 mks
You can get the soft copy for this course or the exam summary answers for this course from 08039407882
Exam summary sample below
